Morbid obesity is a difficult to treat chronic condition defined by a body mass index (BMI=mass/height2 [kg/m2]) greater than 40. For obese persons, excessive weight is commonly associated with increased risk of cardiovascular disease, diabetes, degenerative arthritis, endocrine and pulmonary abnormalities, gallbladder disease and hypertension. Additionally, such persons are highly likely to experience psychological difficulties because of lifestyle restrictions such as reduced mobility and physical capacity, due to back pain, joint problems, and shortness of breath. In severe cases, this can contribute to absenteeism and unemployment. Moreover, impairment of body image can lead to significant psychological disturbances. Repeated failures of dieting and exercise to resolve the problem of obesity can result in feelings of despair and the development of clinical depression.
Bariatric surgery is often recommended for persons suffering from morbid obesity. Preferably, the invasive treatment is accompanied by changes in lifestyle, such as improved regulation of eating habits and an appropriate exercise regimen. Such lifestyle changes are dependent upon the self-discipline and cooperation of the patient.
A book entitled, Textbook of Gastroenterology, 3rd edition, edited by Yamada (Lippincott, Williams & Wilkins), which is incorporated herein by reference, has in Chapter 10 thereof a description of the physiology of gastric motility and gastric emptying.
An abstract entitled, “Gastric myoelectrical pacing as therapy for morbid obesity: Preliminary results,” by Cigaina et al., retrieved on Dec. 24, 2000 from the Web-site http://www.med-online.com/transneuronix/Product/abstract.htm, which is incorporated herein by reference, describes a method for applying monopolar and bipolar gastric stimulation to achieve weight loss.
An abstract entitled, “Implantable gastric stimulator (IGS) as therapy for morbid obesity: Equipment, surgical technique and stimulation parameters,” by Cigaina et al., retrieved on Dec. 24, 2000 from the Web-site http://www.med-online.com/transneuronix/Product/abstract.htm, which is incorporated herein by reference, describes techniques of electrical signal therapy designed to treat obesity.
US Patent 6,129,685 to Howard, which is incorporated herein by reference, describes apparatus and methods for regulating appetite by electrical stimulation of the hypothalamus and by microinfusion of an appropriate quantity of a suitable drug to a distinct site or region within the hypothalamus.
U.S. Pat. No. 4,823,808 to Clegg et al., which is incorporated herein by reference, describes a method for treating obesity, including receiving a physiological measurement and generating audio or visual feedback for the patient to hear or see. The feedback is used for purposes of teaching behavior modification.
U.S. Pat. No. 5,868,141 to Ellias, which is incorporated herein by reference, describes an endoscopic stomach insert for reducing a patient's desire to eat.
U.S. Pat. No. 6,067,991 to Forsell, U.S. Pat. No. 5,601,604 to Vincent, U.S. Pat. No. 5,234,454 to Bangs, U.S. Pat. No. 4,133,315 to Berman et al., U.S. Pat. No. 4,416,267 to Garren et al., and U.S. Pat. Nos. 4,592,339, 5,449,368, 5,226,429 and 5,074,868 to Kuzmak, which are incorporated herein by reference, describe mechanical instruments for implantation in or around the stomach of an obese patient.
U.S. Pat. No. 5,690,691 to Chen et al., which is incorporated herein by reference, describes a gastric pacemaker for treating obesity and other disorders. The pacemaker includes multiple electrodes which are placed at various positions on the gastrointestinal (GI) tract, and deliver phased electrical stimulation to pace peristaltic movement of material through the GI tract.
U.S. Pat. No. 5,423,872 to Cigaina, which is incorporated herein by reference, describes apparatus for applying electrical pulses to the distal gastric antrum of a patient, so as to reduce the motility of the stomach and to thereby treat obesity or another disorder.
U.S. Pat. Nos. 5,188,104 and 5,263,480 to Wernicke et al., which are incorporated herein by reference, describe a method for stimulating the vagus nerve of a patient so as to alleviate an eating disorder.
U.S. Pat. Nos. 6,104,955, 6,091,992, and 5,836,994 to Bourgeois, U.S. Pat. No. 6,026,326 to Bardy, and U.S. Pat. No. 3,411,507 to Wingrove, which are incorporated herein by reference, describe the application of electrical signals to the GI tract to treat various physiological disorders.
U.S. Pat. No. 5,979,449 to Steer, which is incorporated herein by reference, describes an oral appliance for appetite suppression.
U.S. Pat. No. 4,975,682 to Kerr et al., which is incorporated herein by reference, describes apparatus for food intake regulation which is external to the body and which is based upon the voluntary cooperation of the subject in order to be effective.
U.S. Pat. No. 5,861,014 to Familoni, U.S. Pat. No. 5,716,385 to Mittal et al., and U.S. Pat. No. 5,995,872 to Bourgeois, are incorporated herein by reference, and describe methods and apparatus for stimulation of tissue, particularly gastrointestinal tract tissue.
PCT Patent Publication WO 98/10830 to Ben-Haim et al., entitled, “Fencing of cardiac muscles,” and U.S. patent application Ser. No. 09/254,903 in the national phase thereof, both of which are assigned to the assignee of the present patent application and are incorporated herein by reference, describe various methods for controlling the behavior of muscle tissue, for example by blocking or altering the transmission of signals therethrough.
PCT Patent Publication WO 99/03533 to Ben-Haim et al., entitled, “Smooth muscle controller,” and U.S. patent application Ser. No. 09/481,253 in the national phase thereof, both of which are assigned to the assignee of the present patent application and are incorporated herein by reference, describe apparatus and methods for applying signals to smooth muscle so as to modify the behavior thereof. In particular, apparatus for controlling the stomach is described in which a controller applies an electrical field to electrodes on the stomach wall so as to modify the reaction of muscle tissue therein to an activation signal, while not generating a propagating action potential in the tissue. In the context of the present patent application and in the claims, the use of such a non-excitatory signal to modify the response of one or more cells to electrical activation thereof, without inducing action potentials in the cells, is referred to as Excitable-Tissue Control (ETC). Use of an ETC signal is described in the PCT Patent Publication with respect to treating obesity, by applying the ETC signal to the stomach so as to delay or prevent emptying of the stomach. In addition, a method is described for increasing the motility of the gastrointestinal tract, by applying an ETC signal to a portion of the tract in order to increase the contraction force generated in the portion.